Cathode-ray tube sweep circuit



July 22, 1952 v. c. WILSON 2,604,590

CATHODE-RAY TUBE SWEEP CIRCUIT CLAMPING 25 CIRCUIT POWER AMP.

INVENTOR.

VOLNEY C, WlLSON ATTORNEY Patented July 22, 1952 mesne assignments, to the United States of America as represented by the Secretary of the Navy Application October 16, 1945, Serial No. 622,608

2 Claims.

The present invention relates to cathode ray 594,045, for Cathode Ray Tube Sweep Circuit.

plan position indicator cathode ray tube indicator sweep circuits may be obtained by using sawtooth wave forms the amplitudes of which vary sinusoidally. The present invention provides a sinusoidally varying sawtooth wave series by feeding the output from a sine wave potentiometer of the character disclosed in the application of Paul Rosenberg, .Serial No. 592,795, filed May 9, 1945 to a sawtooth wave generator now Patent No. 2,549,389, issued April 17, 1951.

An object of the present invention is to provide a series of sawtooth waves with varying amplitude, following a sine wave pattern.

Another object of the invention is to provide the combination of a sine Wave potentiometer and a sawtooth wave generator.

These and other objects will be apparent from the following specification when taken with the drawing illustrating one embodiment of the invention.

Referring particularly to the drawing, the reference character I indicates a rotatable wire wound card of a sine wave potentiometer of the character disclosed in the aforesaid application of Paul Rosenberg. A direct current potential is applied to the terminals 2 and 3, and brushes 4, 5, 6, and I, maintained relatively stationary to the card I as it rotates, trace a path, shown by the dotted line 8, with the result that there is a sinusoidally varying output from each of the brushes 4, 5, 6, and I. As shown the brush 1 is connected through a plate resistor II to the plate I2 of an electron tube I3. The cathode M of the electron tube I3 is connected directly to ground. A series of negative input pulses I5 are applied to the grid I6 of the tube l3 through a coupling capacitor ll. The tube I3 is normally maintained conducting by a positive potential applied from a source I8 through a resistor I9.

The output from the tube I3 is connected through a suitable clamping circuit and an amplifier 2| to one of the deflecting plates 22 of the cathode ray tube indicator 23. A capacitor 25 is connected to the output of the tube I 3 through a resistor 26 to ground.

In the operation of the circuit, the grid I6 is driven sharply negative below cutofi by one of the pulses l5. This results in the raising of 2 the potential of the plate l2 to provide the straight portion 30 of the sawtooth wave from the output of the tube I3. The condenser 25 starts charging and continues to charge, thereby providing the slope 3| of the sawtoothwave until the pulse [5 goes positive at which time the tube l3 conducts, discharging the condenser 25 to ground and terminating the slope 3| of the sawtooth wave form.

The amplitude of each sawtooth wave produced. is determined by the potential difference between the brush 1 and zero. Hence, as the sine wave potentiometer I rotates the voltage "amplitude of the sawtooth wave form generated will vary sinusoidally as shown by the wave form 32.

The clamping circuit 20 is for the usual purpose of starting the sawtooth wave form at the same potential each time. As shown only one horizontal deflecting plate of the cathode ray tube indicator is energized by the circuit illustrated. It will be understood that opposed plates may be connected in push-pull and that the vertical plates will be suitably energized. The sine Wave outputs from the brushes 4, 5, and 6 may be used in combination with sawtooth generators for this purpose.

Having thus described my invention, what I desire to secure by Letters Patent and claim is:

1. A circuit for producing a succession of sinusoidally modulated sawtooth signals comprising, a sawtooth generator having at least an anode, a cathode and a control grid, a storage condenser resistively connected between said anode and a point of reference potential, means for biasing said tube for maintaining said" tube normally conducting, means for applying synchronizing pulses to said control grid for rendering said tube non-conducting for the period of each pulse to determine the recurrence rate of said sawtooth signals, a source of direct potential, and means including a sine potentiometer connecting said source of direct potential to the anode of said tube, said potentiometer being arranged to sinusoidally vary the magnitude of the anode potential of said tube and accordingly the amplitude of the sawtooth signal appearing at said anode at a substantially lower frequency than the recurrence rate of said sawtooth signals.

2. A circuit for producing a sinusoidally modulated series of sawtooth waves comprising, a source of positive potential, a sine potentiometer, means connecting said source of potential to said potentiometer, said potentiometer being constructed to produce upon rotation at an output terminal thereof a voltage of positive polarity and sinusoidall y' Varying magnitude, a sawtooth generator including an electron tube having at least an anode, a cathode and a control grid, means including an anode resistor connecting said output terminal to said anode, a resistance-capacitance time constant circuit connected between said anode and a point of reference potential, means for biasing said tube to be normally conducting, and means for applying a succession of synchronizing pulses to said control grid for rendering said tube non-conducting for the period of each pulse. 4

VOLNEY C. WILSON REFERENCES CITED The following references are of record in the Number Name Date 1,955,332 Iams 1 1 Apr. 17, 1934 l 2,042,33g Fijschen-efial; May. 26, 1936 2,395,966 Goldberg Mar. 5, 1946 2,411,030 De Ryder Nov. 12, 1946 2,436,899 Higinbotham Mar. 2, 1948 2,437,970 Reich Mar. 16, 1948 

